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On Certainty (2)

Here is the second part of the book On Certainty by Ludwig Wittgenstein.

369. If I wanted to doubt whether this was my hand, how could I avoid doubting whether the word “hand” has any meaning? So that is something I seem to knowafter all.

370. But more correctly: The fact that I use the word “hand” and all the other words in my sentence without a second thought, indeed that I should stand before the abyss if I wanted so much as to try doubting their meanings – shows that absence of doubt belongs to the essence of the language-game, that the question “How do I know…” drags out the language-game, or else does away with it.

371. Doesn’t “I know that that’s a hand”, in Moore’s sense, mean the same, or more or less the same, as: I can make statements like “I have a pain in this hand” or ‘this hand is weaker than the other” or “I once broke this hand”, and countless others, in language-games where a doubt as to the existence of this hand does not come in?

372. Only in certain cases is it possible to make an investigation “is that really a hand?” (or “my hand”). For “I doubt whether that is really my (or a) hand” makes no sense without some more precise determination. One cannot tell from these words alone whether any doubt at all is meant – nor what kind of doubt.

373. Why is it supposed to be possible to have grounds for believing something if it isn’t possible to be certain?

374. We teach a child “that is your hand”, not “that is perhaps (or “probably”) your hand”. That is how a child learns the innumerable language-games that are concerned with his hand. An investigation or question, ‘whether this is really a hand’ never occurs to him. Nor, on the other hand, does he learn that he knows that this is a hand.

375. Here one must realize that complete absence of doubt at some point, even where we would say that ‘legitimate’ doubt can exist, need not falsify a language-game. For there is also something like another arithmetic.
I believe that this admission must underlie any understanding of logic.

376. I may claim with passion that I know that this (for example) is my foot.

377. But this passion is after all something very rare, and there is no trace of it when I talk of this foot in the ordinary way.

378. Knowledge is in the end based on acknowledgement.

379. I say with passion “I know that this is a foot” – but what does it mean?

380. I might go on: “Nothing in the world will convince me of the opposite!” For me this fact is at the bottom of all knowledge. I shall give up other things but not this.

381. This “Nothing in the world” is obviously an attitude which one hasn’t got towards everything one believes or is certain of.

382. That is not to say that nothing in the world will in fact be able to convince me of anything else.

383. The argument “I may be dreaming” is senseless for this reason: if I am dreaming, this remark is being dreamed as well – and indeed it is also being dreamed that these words have any meaning.

384. Now what kind of sentence is “Nothing in the world…”?

385. It has the form of a prediction, but of course it is not one that is based on experience.

386. Anyone who says, with Moore, that he knows that so and so… – gives the degree of certainty that something has for him. And it is important that this degree has a maximum value.

387. Someone might ask me: “How certain are you that that is a tree over there; that you have money in your pocket; that that is your foot?” And the answer in one case might be “not certain”, in another “as good as certain”, in the third “I can’t doubt it”. And these answers would make sense even without any grounds. I should not need for example, to say: “I can’t be certain whether that is a tree because my eyes aren’t sharp enough.” I want to say: it made sense for Moore to say “I know that that is a tree”, if he meant something quite particular by it.

[I believe it might interest a philosopher, one who can think himself, to read my notes. For even if I have hit the mark only rarely, he would recognize what targets I had been ceaselessly aiming at.]

388. Every one of us often uses such a sentence, and there is no question but that it makes sense. But does that mean it yields any philosophical conclusion? Is it more of a proof of the existence of external things, that I know that this is a hand, than that I don’t know whether that is gold or brass?

389. Moore wanted to give an example to show that one really can knowpropositions about physical objects. – If there were a dispute whether one could have a pain in such and such a part of the body, then someone who just then had a pain in that spot might say: “I assure you, I have a pain there now.” But it would sound odd if Moore had said: “I assure you, I know that’s a tree.” A personal experience simply has no interest for us here.

390. All that is important is that it makes sense to say that one knows such a thing; and consequently the assurance that one does know it can’t accomplish anything here.

391. Imagine a language-game “When I call you, come in through the door.” In any ordinary case, a doubt whether there really is a door there will be impossible.

392. What I need to show is that a doubt is not necessary even when it is possible. That the possibility of the language-game doesn’t depend on everything being doubted that can be doubted. (This is connected with the role of contradiction in mathematics.)

393. The sentence “I know that that’s a tree” if it were said outside its language-game, might also be a quotation (from an English grammar-book perhaps). – “But suppose I mean it while I am saying it?” The old misunderstanding about the concept ‘mean’.

394. “This is one of the things that I cannot doubt.”

395. “I know all that.” And that will come out in the way I act and in the way I speak about the things in question.

396. In the language-game (2), can he say that he knows that those are building stones? – “No, but he does know it.” [[Philosophical Investigations I,2: … and write with confidence “In the beginning was the deed.” Goethe, Faust I. ]]

397. Haven’t I gone wrong and isn’t Moore perfectly right? Haven’t I made the elementary mistake of confusing one’s thoughts with one’s knowledge? Of course I do not think to myself “The earth already existed for some time before my birth”, but do I know it any the less? Don’t I show that I know it by always drawing its consequences?

398. And don’t I know that there is no stairway in this house going six floors deep into the earth, even though I have never thought about it?

399. But doesn’t my drawing the consequences only show that I accept this hypothesis?

400. Here I am inclined to fight windmills, because I cannot yet say the thing I really want to say.

401. I want to say: propositions of the form of empirical propositions, and not only propositions of logic, form the foundation of all operating with thoughts (with language). – This observation is not of the form “I know…”. “I know…” states what I know, and that is not of logical interest.

402. In this remark the expression “propositions of the form of empirical propositions” is itself thoroughly bad; the statements in question are statements about material objects. And they do not serve as foundations in the same way as hypotheses which, if they turn out to be false, are replaced by others.

403. To say of man, in Moore’s sense, that he knows something; that what he says is therefore unconditionally the truth, seems wrong to me. – It is the truth only inasmuch as it is an unmoving foundation of his language-games.

404. I want to say: it’s not that on some points men know the truth with perfect certainty. No: perfect certainty is only a matter of their attitude.

405. But of course there is still a mistake even here.

406. What I am aiming at is also found in the difference between the casual observation “I know that that’s a…”, as it might be used in ordinary life, and the same utterance when a philosopher makes it.

407. For when Moore says “I know that that’s…” I want to reply “you don’t know anything!” – and yet I would not say that to anyone who was speaking without philosophical intention. That is, I feel (rightly?) that these two mean to say something different.

408. For if someone says he knows such-and-such, and this is part of his philosophy – then his philosophy is false if he has slipped up in this statement.

409. If I say “I know that that’s a foot” – what am I really saying? Isn’t the whole point that I am certain of the consequences – that if someone else had been in doubt I might say to him “you see – I told you so”? Would my knowledge still be worth anything if it let me down as a clue in action? And can’t it let me down?

410. Our knowledge forms an enormous system. And only within this system has a particular bit the value we give it.

411. If I say “we assume that the earth has existed for many years past” (or something similar), then of course it sounds strange that we should assume such a thing. But in the entire system of our language-games it belongs to the foundations. The assumption, one might say, forms the basis of action, and therefore, naturally, of thought.

412. Anyone who is unable to imagine a case in which one might say “I know that this is my hand” (and such cases are certainly rare) might say that these words were nonsense. True, he might also say “Of course I know – how could I not know?” – but then he would possibly be taking the sentence “this is my hand” as an explanation of the words “my hand”.

413. For suppose you were guiding a blind man’s hand, and as you were guiding it along yours you said “this is my hand”; if he then said “are you sure?” or “do you know it is?”, it would take very special circumstances for that to make sense.

414. But on the other hand: how do I know that it is my hand? Do I even here know exactly what it means to say it is my hand? – When I say “how do I know?” I do not mean that I have the least doubt of it. What we have here is a foundation for all my action. But it seems to me that it is wrongly expressed by the words “I know”.

415. And in fact, isn’t the use of the word “know” as a preeminently philosophical word altogether wrong? If “know” has this interest, why not “being certain”? Apparently because it would be too subjective. But isn’t “know” just as subjective? Isn’t one misled simply by the grammatical peculiarity that “p” follows from “I know p”? “I believe I know” would not need to express a lesser degree of certainty. – True, but one isn’t trying to express even the greatest subjective certainty, but rather that certain propositions seem to underlie all questions and all thinking.

416. And have we an example of this in, say, the proposition that I have been living in this room for weeks past, that my memory does not deceive me in this?
– “certain beyond all reasonable doubt” –

417. “I know that for the last month I have had a bath every day.” What am I remembering? Each day and the bath each morning? No. I knowthat I bathed each day and I do not derive that from some other immediate datum. Similarly I say “I felt a pain in my arm” without this locality coming into my consciousness in any other way (such as by means of an image).

418. Is my understanding only blindness to my own lack of understanding? It often seems so to me.

419. If I say “I have never been in Asia Minor”, where do I get this knowledge from? I have not worked it out, no one told me; my memory tells me. – So I can’t be wrong about it? Is there a truth here which I know? – I cannot depart from this judgment without toppling all other judgments with it.

420. Even a proposition like this one, that I am now living in England, has these two sides: it is not a mistake – but on the other hand, what do I know of England? Can’t my judgment go all to pieces? Would it not be possible that people came to my room and all declared the opposite? – even gave me ‘proofs’ of it, so that I suddenly stood there like a madman alone among people who were all normal, or a normal person alone among madmen? Might I not then suffer doubts about what at present seems at the furthest remove from doubt?

421. I am in England. – Everything around me tells me so; wherever and however I let my thoughts turn, they confirm this for me at once. – But might I not be shaken if things such as I don’t dream of at present were to happen?

422. So I am trying to say something that sounds like pragmatism.
Here I am being thwarted by a kind of Weltanschauung.

423. Then why don’t I simply say with Moore “I know that I am in England?” Saying this is meaningful in particular circumstances, which I can imagine. But when I utter the sentence outside these circumstances, as an example to show that I can know truths of this kind with certainty, then it at once strikes me as fishy. – Ought it to?

424. I say “I know p” either to assure people that I, too, know the truth p, or simply as an emphasis of |-p. One says too, “I don’t believe it, I know it”. And one might also put it like this (for example): “That is a tree. And that’s not just surmise.” But what about this: “If I were to tell someone that that was a tree, that wouldn’t be just surmise.” Isn’t this what Moore was trying to say?

425. It would not be surmise and I might tell it to someone else with complete certainty, as something there is no doubt about. But does that mean that it is unconditionally the truth? May not the thing that I recognize with complete certainty as the tree that I have seen here my whole life long – may this not be disclosed as something different? May it not confound me? And nevertheless it was right, in the circumstances that give this sentence meaning, to say “I know (I do not merely surmise) that that’s a tree.” To say that in strict truth I only believe it, would be wrong. It would be completely misleading to say: “I believe my name is L.W.” And this too is right: I cannot be making a mistake about it. But that does not mean that I am infallible about it.

426. But how can we show someone that we know truths, not only about sense-data but also about things? For after all it can’t be enough for someone to assure us that he knows this. Well, what must our starting point be if we are to show this?

427. We need to show that even if he never uses the words “I know…”, his conduct exhibits the thing we are concerned with.

428. For suppose a person of normal behavior assured us that he only believed his name was such-and-such, he believed he recognized the people he regularly lived with, he believed that he had hands and feet when he didn’t actually see them, and so on. Can we show him it is not so from the things he does (and says)?

429. What reason have I, now, when I cannot see my toes, to assume that I have five toes on each foot?

Is it right to say that my reason is that previous experience has always taught me so? Am I more certain of previous experience than that I have ten toes?
That previous experience may very well be the causeof my present certitude; but is it its ground?

430. I meet someone from Mars and he asks me “How many toes have human beings got?” – I say “Ten. I’ll show you”, and take my shoes off. Suppose he was surprised that I knew with such certainty, although I hadn’t looked at my toes – ought I to say: “We humans know how many toes we have whether we can see them or not”?

431. “I know that this room is on the second floor, that behind the door a short landing leads to the stairs, and so on.” One could imagine cases where I should come out with this, but they would be extremely rare. But on the other hand I show this knowledge day in, day out by my actions and also in what I say.

Now what does someone else gather from these actions and words of mine? Won’t it be just that I am sure of my ground? – From the fact that I have been living here for many weeks and have gone up and down the stairs every day he will gather that I know where my room is situated. – I shall give him the assurance “I know” when he does notalready know things which would have compelled the conclusion that I knew.

432. The utterance “I know…” can only have its meaning in connection with the other evidence of my ‘knowing’.

433. So if I say to someone “I know that that’s a tree”, it is also as if I told him “that is a tree; you can absolutely rely on it; there is no doubt about it”. And a philosopher could only use the statement to show that this form of speech is actually used. But if his use of it is not to be merely an observation about English grammar, he must give the circumstances in which this expression functions.

434. Now does experience teach us that in such-and-such circumstances people know this and that? Certainly, experience shows us that normally after so-and-so many days a man can find his way about a house he has been living in. Or even: experience teaches us that after such-and-such a period of training a man’s judgment is to be trusted. He must, experience tells us, have learnt for so long in order to be able to make a correct prediction. But —–.

435. One is often bewitched by a word. For example, by the word “know”.

436. Is God bound by our knowledge? Are a lot of our statements incapable of falsehood? For that is what we want to say.

437. I am inclined to say: “That cannot be false.” That is interesting. But what consequences has it?

438. It would not be enough to assure someone that I know what is going on at a certain place – without giving him grounds that satisfy him that I am in a position to know.

439. Even the statement “I know that behind this door there is a landing and the stairway down to the ground floor” only sounds so convincing because everyone takes it for granted that I know it.

440. There is something universal here; not just something personal.

441. In a court of law the mere assurance “I know…” on the part of a witness would convince no one. It must be shown that he was in a position to know.
Even the assurance “I know that that’s a hand”, said while someone looked at his own hand, would not be credible unless we knew the circumstances in which it was said. And if we do know them, it seems to be an assurance that the person speaking is normal in this respect.

442. For may it not happen that I imagine myself to know something?

443. Suppose that in a certain language there were no word corresponding to our “know”. – The people simply make assertions. (“That is a tree”, etc.) Naturally it can occur for them to make mistakes. And so they attach a sign to the sentence which indicates how probable they take a mistake to be – or should I say, how probable a mistake is in this case? This latter can also be indicated by mentioning certain circumstances. For example “Then A said to B ‘…’ I was standing quite close to them and my hearing is good”, or “A was at such-and-such a place yesterday. I saw him from a long way off. My eyes are not very good”, or “There is a tree over there: I can see it clearly and I have seen it innumerable times before”.

444. “The train leaves at two o’clock. Check it once more to make certain” or “The train leaves at two o’clock. I have just looked it up in a new time-table.” One may also add “I am reliable in such matters”. The usefulness of such additions is obvious.

445. But if I say “I have two hands”, what can I add to indicate reliability? At the most that the circumstances are the ordinary ones.

446. But why am I so certain that this is my hand? Doesn’t the whole language-game rest on this kind of certainty? Or: isn’t this ‘certainty’ (already) presupposed in the language-game? Namely by virtue of the fact that one is not playing the game, or is playing it wrong, if one does not recognize objects with certainty.

447. Compare with this 12×12=144. Here too we don’t say “perhaps”. For, in so far as this proposition rests on our not miscounting or miscalculating and on our senses not deceiving us as we calculate, both propositions, the arithmetical one and the physical one, are on the same level.

I want to say: The physical game is just as certain as the arithmetical. But this can be misunderstood. My remark is a logical and not a psychological one.

448. I want to say: If one doesn’t marvel at the fact that the propositions of arithmetic (e.g. the multiplication tables) are ‘absolutely certain’, then why should one be astonished that the proposition “This is my hand” is so equally?

449. Something must be taught us as a foundation.

450. I want to say: our learning has the form “that is a violet”, “that is a table”. Admittedly, the child might hear the word “violet” for the first time in the sentence “perhaps that is a violet”, but then he could ask “what is a violet?” Now this might of course be answered by showing him a picture. But how would it be if one said “that is a…” only when showing him a picture, but otherwise said nothing but “perhaps that is a…” – What practical consequences is that supposed to have? A doubt that doubted everything would not be a doubt.

451. My objection against Moore, that the meaning of the isolated sentence “That is a tree” is undetermined, since it is not determined what the “that” is that is said to be a tree – doesn’t work, for one can make the meaning more definite by saying, for example: “The object over there that looks like a tree is not an artificial imitation of a tree but a real one.”

452. It would not be reasonable to doubt if that was a real tree or only…
My finding it beyond doubt is not what counts. If a doubt would be unreasonable, that cannot be seen from what I hold. There would therefore have to be a rule that declares doubt to be unreasonable here. But there isn’t such a rule, either.

453. I do indeed say: “Here no reasonable person would doubt.” – Could we imagine learned judges being asked whether a doubt was reasonable or unreasonable?

454. There are cases where doubt is unreasonable, but others where it seems logically impossible. And there seems to be no clear boundary between them.

455. Every language-game is based on words ‘and objects’ being recognized again. We learn with the same inexorability that is a chair as that 2×2=4.

456. If, therefore, I doubt or am uncertain about this being my hand (in whatever sense), why not in that case about the meaning of these words as well?

457. Do I want to say, then, that certainty resides in the nature of the language-game?

458. One doubts on specific grounds. The question is this: how is doubt introduced into the language-game?

459. If the shopkeeper wanted to investigate each of his apples without any reason, for the sake of being certain about everything, why doesn’t he have to investigate the investigation? And can one talk of belief here (I mean belief as in ‘religious belief’, not surmise)? All psychological terms merely distract us from the thing that really matters.

460. I go to the doctor, show him my hand and say “This is a hand, not…; I’ve injured it, etc.,etc.” Am I only giving him a piece of superfluous information? For example, mightn’t one say: supposing the words “This is a hand” were a piece of information – how could you bank on his understanding this information? Indeed, if it is open to doubt ‘whether that is a hand’, why isn’t it also open to doubt whether I am a human being who is informing the doctor of this? – But on the other hand one can imagine cases – even if they are very rare ones – where this declaration is not superfluous, or is only superfluous but not absurd.

461. Suppose that I were the doctor and a patient came to me, showed me his hand and said: “This thing that looks like a hand isn’t just a superb imitation – it really is a hand” and went on to talk about his injury – should I really take this as a piece of information, even though a superfluous one? Shouldn’t I be more likely to consider it nonsense, which admittedly did have the form of a piece of information? For, I should say, if this information really were meaningful, how can he be certain of what he says? The background is lacking for it to be information.

462. Why doesn’t Moore produce as one of the things that he knows, for example, that is such-and-such a part of England there is a village called so-and-so? In other words: why doesn’t he mention a fact that is known to him and not to every oneof us?

463. This is certainly true, that the information “That is a tree”, when no one could doubt it, might be a kind of joke and as such have meaning. A joke of this kind was in fact made once by Renan.

464. My difficulty can also be shown like this: I am sitting talking to a friend. Suddenly I say: “I knew all along that you were so-and-so.” Is that really just a superfluous, though true, remark?

I feel as if these words were like “Good morning” said to someone in the middle of a conversation.

465. How would it be if we had the words “They know nowadays that there are over…species of insects” instead of “I know that that’s a tree”? If someone were suddenly to utter the first sentence out of all context one might think: he has been thinking of something else in the interim and is now saying out loud some sentence in his train of thought. Or again: he is in a trance and is speaking without understanding what he is saying.

466. Thus it seems to me that I have known something the whole time, and yet there is no meaning in saying so, in uttering this truth.

467. I am sitting with a philosopher in the garden; he says again and again “I know that that’s a tree”, pointing to a tree that is near us. Someone else arrives and hears this, and I tell him: “This fellow isn’t insane. We are only doing philosophy.”

468. Someone says irrelevantly “That’s a tree”. He might say this sentence because he remembers having heard it in a similar situation; or he was suddenly struck by the tree’s beauty and the sentence was an exclamation; or he was pronouncing the sentence to himself as a grammatical example;etc.,etc. And now I ask him “How did you mean that?” and he replies “It was a piece of information directed at you.” Shouldn’t I be at liberty to assume that he doesn’t know what he is saying, if he is insane enough to want to give me this information?

469. In the middle of a conversation, someone says to me out of the blue: “I wish you luck.” I am astonished; but later I realize that these words connect up with his thoughts about me. And now they do not strike me as meaningless any more.

470. Why is there no doubt that I am called L.W.? It does not seem at all like something that one could establish at once beyond doubt. One would not think that it is one of the indubitable truths.

[Here there is still a big gap in my thinking. And I doubt whether it will be filled now.]

471. It is so difficult to find the beginning. Or, better: it is difficult to begin at the beginning. And not try to go further back.

472. When a child learns language it learns at the same time what is to be investigated and what not. When it learns that there is a cupboard in the room, it isn’t taught to doubt whether what it sees later on is still a cupboard or only a kind of stage set.

473. Just as in writing we learn a particular basic form of letters and then vary it later, so we learn first the stability of things as the norm, which is then subject to alterations.

474. This games proves its worth. That may be the cause of its being played, but it is not the ground.

475. I want to regard man here as an animal; as a primitive being to which one grants instinct but not ratiocination. As a creature in a primitive state. Any logic good enough for a primitive means of communication needs no apology from us. Language did not emerge from some kind of ratiocination [Raisonnement].

476. Children do not learn that books exist, that armchairs exist, etc.,etc. – they learn to fetch books, sit in armchairs, etc.,etc.

Later, questions about the existence of things do of course arise, “Is there such a thing as a unicorn?” and so on. But such a question is possible only because as a rule no corresponding question presents itself. For how does one know how to set about satisfying oneself of the existence of unicorns? How did one learn the method for determining whether something exists or not?

477. “So one must know that the objects whose names one teaches a child by an ostensive definition exist.” – Why must one know they do? Isn’t it enough that experience doesn’t later show the opposite?
For why should the language-game rest on some kind of knowledge?

478. Does a child believe that milk exists? Or does it know that milk exists? Does a cat know that a mouse exists?

479. Are we to say that the knowledge that there are physical objects comes very early or very late?

480. A child that is learning to use the word “tree”. One stands with it in front of a tree and says “Lovely tree!” Clearly no doubt as to the tree’s existence comes into the language-game. But can the child be said to know: ‘that a tree exists’? Admittedly it’s true that ‘knowing something’ doesn’t involve thinkingabout it – but mustn’t anyone who knows something be capable of doubt? And doubting means thinking.

481. When one hears Moore say “I know that that’s a tree”, one suddenly understands those who think that that has by no means been settled.
The matter strikes one all at once as being unclear and blurred. It is as if Moore had put it in the wrong light. It is as if I were to see a painting (say a painted stage-set) and recognize what it represents from a long way off at once and without the slightest doubt. But now I step nearer: and then I see a lot of patches of different colours, which are all highly ambiguous and do not provide any certainty whatever.

482. It is as if “I know” did not tolerate a metaphysical emphasis.

483. The correct use of the expression “I know”. Someone with bad sight asks me: “do you believe that the thing we can see there is a tree?” I reply “I know it is; I can see it clearly and am familiar with it.” – A: “Isn’t N.N. at home?” – I: “I believe he is.” – A: “Was he at home yesterday?” – I; “Yesterday he was – I know he was; I spoke to him.” – A: “Do you know or only believe that this part of the house is built on later than the rest?” – I: “I know it is; I got it from so and so.”

484. In these cases, then, one says “I know” and mentions how one knows, or at least one can do so.

485. We can also imagine a case where someone goes through a list of propositions and as he does so keeps asking “Do I know that or do I only believe it?” He wants to check the certainty of each individual proposition. It might be a question of making a statement as a witness before a court.

486. “Do you know or do you only believe that your name is L.W.?” Is that a meaningful question?

Do you know or do you only believe that what you are writing down now are German words? Do you only believe that “believe” has this meaning? What meaning?

487. What is the proof that I know something? Most certainly not my saying I know it.

488. And so, when writers enumerate all the things they know, that proves nothing whatever.
So the possibility of knowledge about physical objects cannot be proved by the protestations of those who believe that they have such knowledge.

489. For what reply does one make to someone who says “I believe it merely strikes you as if you knew it”?

490. When I ask “Do I know or do I only believe that I am called…?” it is no use to look within myself.
But I could say: not only do I never have the slightest doubt that I am called that, but there is no judgement I could be certain of if I started doubting about that.

491. “Do I know or do I only believe that I am called L.W.?” – Of course, if the question were “Am I certain or do I only surmise…?”, then my answer could be relied on.

492. “Do I know or do I only believe…?” might also be expressed like this: What if it seemed to turn out that what until now has seemed immune to doubt was a false assumption? Would I react as I do when a belief has proved to be false? or would it seem to knock from under my feet the ground on which I stand in making any judgements at all? – But of course I do not intend this as a prophecy.
Would I simply say “I should never have thought it!” – or would I (have to) refuse to revise my judgement – because such a ‘revision’ would amount to annihilation of all yardsticks?

493. So is this it: I must recognize certain authorities in order to make judgements at all?

494. “I cannot doubt this proposition without giving up all judgement.”
But what sort of proposition is that? (It is reminiscent of what Frege said about the law of identity.) It is certainly no empirical proposition. It does not belong to psychology. It has rather the character of a rule.

495. One might simply say “O, rubbish!” to someone who wanted to make objections to the propositions that are beyond doubt. That is, not reply to him but admonish him.

496. This is a similar case to that of showing that it has no meaning to say that a game has always been played wrong.

497. If someone wanted to arouse doubts in me and spoke like this: here your memory is deceiving you, there you’ve been taken in, there again you have not been thorough enough in satisfying yourself, etc., and if I did not allow myself to be shaken but kept to my certainty – then my doing so cannot be wrong, even if only because this is just what defines a game.

498. The queer thing is that even though I find it quite correct for someone to say “Rubbish!” and so brush aside the attempt to confuse him with doubts at bedrock, – nevertheless, I hold it to be incorrect if he seeks to defend himself (using, e.g., the words “I know”).

499. I might also put it like this: the ‘law of induction’ can no more be grounded than certain particular propositions concerning the material of experience.

500. But it would also strike me as nonsense to say “I know that the law of induction is true”. Imagine such a statement made in a court of law! It would be more correct to say “I believe in the law of…” where ‘believe’ has nothing to do with surmising.

501. Am I not getting closer and closer to saying that in the end logic cannot be described? You must look at the practice of language, then you will see it.

502. Could one say “I know the position of my hands with my eyes closed”, if the position I gave always or mostly contradicted the evidence of other people?

503. I look at an object and say “That is a tree”, or “I know that that’s a tree”. – Now if I go nearer and it turns out that it isn’t, I may say “It wasn’t a tree at all” or alternatively I say “It was a tree but now it isn’t any longer”. But if all the others contradicted me, and said it never had been a tree, and if all the other evidences spoke against me – what good would it do to me to stick to my “I know”?

504. Whether I know something depends on whether the evidence backs me up or contradicts me. For to say one knows one has a pain means nothing.

505. It is always by favour of Nature that one knows something.

506. “If my memory deceives me here it can deceive me everywhere.”
If I don’t know that, how do I know if my words mean what I believe they mean?

507. “If this deceives me, what does ‘deceive’ mean any more?”

508. What can I rely on?

509. I really want to say that a language-game is only possible if one trusts something (I did not say “can trust something”).

510. If I say “Of course I know that that’s a towel” I am making an utterance. I have no thought of a verification. For me it is an immediate utterance.
I don’t think of past or future. (And of course it’s the same for Moore, too.)
It is just like directly taking hold of something, as I take hold of my towel without having doubts.

511. And yet this direct taking-hold corresponds to a sureness, not to a knowing. But don’t I take hold of a thing’s name like that, too?

512. Isn’t the question this: “What if you had to change your opinion even on these most fundamental things?” And to that the answer seems to me to be: “You don’t haveto change it. That is just what their being ‘fundamental’ is.”

513. What if something really unheard-of happened? – If I, say, saw houses gradually turning into steam without any obvious cause, it the cattle in the fields stood on their heads and laughed and spoke comprehensible words; if trees gradually changed into men and men into trees. Now, was I right when I said before all these things happened “I know that that’s a house” etc., or simply “that’s a house” etc.?

514. This statement appeared to me fundamental; if it is false, what are ‘true’ and ‘false’ any more?!

515. If my name is not L.W., how can I rely on what is meant by “true” and “false”?

516. If something happened (such as someone telling me something) calculated to make me doubtful of my own name, there would certainly also be something that made the grounds of these doubts themselves seem doubtful, and I could therefore decide to retain my old belief.

517. But might it not be possible for something to happen that threw me entirely off the rails? Evidence that made the most certain thing unacceptable to me? Or at any rate made me throw over my most fundamental judgements? (Whether rightly or wrongly is beside the point.)

518. Could I imagine observing this in another person?

519. Admittedly, if you are obeying the order “Bring me a book”, you may have to check whether the thing you see over there really is a book, but then you do at least know what people mean by a “book”; and if you don’t you can look it up, – but then you must know what some other word means. And the fact that a word means such-and-such, is used in such-and-such a way, is in turn an empirical fact, like the fact that what you see over there is a book.
Therefore, in order for you to be able to carry out an order there must be some empirical fact about which you are not in doubt. Doubt itself rests only on what is beyond doubt. But since a language-game is something that consists in the recurrent procedures of the game in time, it seems impossible to say in any individual case that such-and-such must be beyond doubt if there is to be a language-game – though it is right enough to say that as a rule some empirical judgment or other must be beyond doubt.

520. Moore has every right to say he knows there’s a tree there in front of him. Naturally he may be wrong. (For it is not the same as with the utterance “I believe there is a tree there”.) But whether he is right or wrong in this case is of no philosophical importance. If Moore is attacking those who say that one cannot really know such a thing, he can’t do it by assuring them that he knows this and that. For one need not believe him. If his opponents had asserted that one could not believe this and that, then he could have replied: “Ibelieve it”.

521. Moore’s mistake lies in this – countering the assertion that one cannot know that, by saying “I do know it”.

522. We say: if a child has mastered language – and hence its application – it must know the meaning of words. It must, for example, be able to attach the name of its colour to white, black, red or blue object without the occurrence of any doubt.

523. And indeed no one misses doubt here; no one is surprised that we do not merely surmise the meaning of our words.

524. Is it essential for our language-games (‘ordering and obeying’ for example) that no doubt appears at certain points, or is it enough if there is the feeling of being sure, admittedly with a slight breath of doubt?

That is, is it enough if I do not, as I do now, call something ‘black’, ‘green’, ‘red’, straight off, without any doubt at all interposing itself – but do instead say “I am sure that is red”, as one may say “I am sure that he will come today” (in other words with the ‘feeling of being sure’)? The accompanying feeling is of course a matter of indifference to us, and equally we have no need to bother about the words “I am sure that” either. – What is important is whether they go with a difference in the practice of the language. One might ask whether a person who spoke like this would always say “I am sure” on occasions where (for example) there is sureness in the reports we make ( in an experiment, for example, we look through a tube and report the colour we see through it). If he does, our immediate inclination will be to check what he says. But if he proves to be perfectly reliable, one will say that his way of talking is merely a bit perverse, and does not affect the issue. One might for example suppose that he has read sceptical philosophers, become convinced that one can know nothing, and that is why he has adopted this way of speaking. Once we are used to it, it does not infect practice.

525. What, then, does the case look like where someone really has got a different relationship to the names of colours, for example, from us? Where, that is, there persists a slight doubt or a possibility of doubt in their use.

526. If someone were to look at an English pillar-box and say “I am sure that it’s red”, we should have to suppose that he was colour-blind, or believe he had no mastery of English and knew the correct name for the colour in some other language.

If neither was the case we should not quite understand him.

527. An Englishman who calls this colour “red” is not ‘sure it is called “red” in English’. A child who has mastered the use of the word is not ‘sure that in his language this colour is called…’. Nor can one say of him that when he is learning to speak he learns that the colour is called that in English; not yet : he knows this when he has learnt the use of the word.

528. And in spite of this: if someone asked me what the colour was called in German and I tell him, and now he asks me “are you sure?” – then I shall reply “I know it is; German is my mother tongue”.

529. And one child, for example, will say, of another or of himself, that he already knows what such-and-such is called.

530. I may tell someone “this colour is called ‘red’ in English” (when for example I am teaching him English). In this case I should not say “I know that this colour…” – I would perhaps say that if I had just now learned it, or by contrast with another colour whose English name I am not acquainted with.

531. But now, isn’t it correct to describe my present state as follows: I know what this colour is called in English? And if that is correct, why then should I not describe my state with the corresponding words “I know etc.”?

532. So when Moore sat in front of a tree and said “I know that that’s a tree”, he was simply stating the truth about this state at the time.

[I do philosophy now like an old woman who is always mislaying something and having to look for it again: now her spectacles, now her keys.]

533. Well, if it was correct to describe his state out of context, then it was just as correct to utter the words “that’s a tree” out of context.

534. But is it wrong to say: “A child that has mastered a language-game must know certain things”? If instead of that one said “must be able to do certain things”, that would be a pleonasm, yet this is just what I want to counter the first sentence with. – But : “a child acquires a knowledge of natural history”. That presupposes that it can ask what such and such a plant is called.

535. The child knows what something is called if he can reply correctly to the question “what is that called?”

536. Naturally, the child who is just learning to speak has not yet got the concept is called at all.

537. Can one say of someone who hasn’t this concept that he knows what such-and-such is called?

538. The child, I should like to say, learns to react in such-and-such a way; and in so reacting it doesn’t so far know anything. Knowing only begins at a later lever.

539. Does it go for knowing as it does for collecting?

540. A dog might learn to run to N at the call “N”, and to M at the call “M”, – but would that mean he knows what these people are called?

541. “He only knows what this person is called – not yet what that person is called”. That is something one cannot, strictly speaking, say of someone who simply has not yet got the concept of people’s having names.

542. “I can’t describe this flower if I don’t know that this colour is called ‘red’. ”

543. A child can use the names of people long before he can say in any form whatever: “I know this one’s name; I don’t know that one’s yet.”

544. Of course I may truthfully say “I know what this colour is called in English”, at the same time as I point (for example) to the colour of fresh blood. But —

545. ‘A child knows which colour is meant by the word “blue”.’ What he knows here is not all that simple.

546. I should say “I know what this colour is called” if e.g. what is in question is shades of colour whose name not everybody knows.

547. One can’t yet say to a child who is just beginning to speak and can use the words “red” and “blue”: “Come on, you know what this colour is called!”

548. A child must learn the use of colour words before it can ask for the name of a colour.

549. It would be wrong to say that I can only say “I know that there is a chair there” when there is a chair there. Of course it isn’t true unless there is, but I have a right to say this if I am sure there is a chair there, even if I am wrong.

[Pretensions are a mortgage which burdens a philosopher’s capacity to think.]

550. If someone believes something, we needn’t always be able to answer the question ‘why he believes it’; but if he knows something, then the question “how does he know?” must be capable of being answered.

551. And if one does answer this question, one must do so according to generally accepted axioms. This is how something of this sort may be known.

552. Do I know that I am now sitting in a chair? – Don’t I know it?! In the present circumstances no one is going to say that I know this; but no more will he say, for example, that I am conscious. Nor will one normally say that of the passers-by in the street. But now, even if one doesn’t say it, does that make it untrue??

553. It is queer: if I say, without any special occasion, “I know” – for example, “I know that I am now sitting in a chair”, this statement seems to me unjustified and presumptuous. But if I make the same statement where there is some need for it, then, although I am not a jot more certain of its truth, it seems to me to be perfectly justified and everyday.

554. In its language-game it is not presumptuous. There, it has no higher position than, simply, the human language-game. For there it has its restricted application. But as soon as I say this sentence outside its context, it appears in a false light. For then it is as if I wanted to insist that there are things that I know. God himself can’t say anything to me about them.

555. We say we know that water boils when it is put over a fire. How do we know? Experience has taught us. – I say “I know that I had breakfeast this morning”; experience hasn’t taught me that. One also says “I know that he is in pain”. The language-game is different every time, we are sure every time, and people will agree with us that we are in a position to know every time. And that is why the propositions of physics are found in textbooks for everyone.

If someone says he knowsomething, it must be something that, by general consent, he is in a position to know.

556. One doesn’t say: he is in a position to believe that.
But one does say: “It is reasonable to assume that in this situation” (or “to believe that”).

557. A court-martial may well have to decide whether it was reasonable in such-and-such a situation to have assumed this or that with confidence (even thought wrongly).

558. We say we know that water boils and does not freeze under such-and-such circumstances. Is it conceivable that we are wrong? Wouldn’t a mistake topple all judgment with it? More: what could stand if that were to fall? Might someone discover something that made us say “It was a mistake”? Whatever may happen in the future, however water may behave in the future, – we know that up to now it has behaved thus in innumerable instances. This fact is fused into the foundations of our language-game.

559. You must bear in mind that the language-game is so to say something unpredictable. I mean: it is not based on grounds. It is not reasonable (or unreasonable). It is there – like our life.

560. And the concept of knowing is coupled with that of the language-game.

561. “I know” and “You can rely on it”. But one cannot always substitute the latter for the former.

562. At any rate it is important to imagine a language in which our concept ‘knowledge’ does not exist.

563. One says “I know that he is in pain” although one can produce no convincing grounds for this. – Is this the same as “I am sure that he…”? – No, “I am sure” tells you my subjective certainty. “I know” means that I who know it, and the person who doesn’t are separated by a difference in understanding. (Perhaps based on a difference in degree of experience.) If I say “I know” in mathematics, the justification for this is a proof.

If in these two cases instead of “I know”, one says “you can rely on it” then the substantiation is of a different kind in each case. And substantiation comes to an end.

564. A language-game: bringing building stones, reporting the number of available stones. The number is sometimes estimated, sometimes established by counting. Then the question arises “Do you believe there are as many stones as that?”, and the answer “I know there are – I’ve just counted them”. But here the “I know” could be dropped. If, however, there are several ways of finding something out for sure, like counting, weighing, measuring the stack, then the statement “I know” can take the place of mentioning how I know.

565. But here there isn’t yet any question of any “knowledge” that this is called “a slab”, this “a pillar”, etc.

566. Nor does a child who learns my language-game (PI No.2) learn to say “I know that this is called ‘a slab’ “. Now of course there is a language-game in which the child uses that sentence. This presupposes that the child is already capable of using the name as soon as he is given it. (As if someone were to tell me “this colour is called…”) – Thus, if the child has learnt a language-game with building stones, one can say something like “and this stone is called…”, and in this way the original language-game has been expanded.

567. And now, is my knowledge that I am called L.W. of the same kind as knowledge that water boils at 100C? Of course, this question is wrongly put.

568. If one of my names were used only very rarely, then it might happen that I did not know it. It goes without saying that I know my name, only because, like anyone else, I use it over and over again.

569. An inner experience cannot show me that I know something.
Hence, if in spite of that I say, “I know that my name is…”, and yet it is obviously not an empirical proposition,—

570. “I know this is my name; among us any grown-up knows what his name is.”

571. “My name is… – you can rely on that. If it turns out to be wrong you need never believe me in the future.”

572. Don’t I seem to know that I can’t be wrong about such a thing as my own name? This comes out in the words: “If that is wrong, then I am crazy”. Very well, but those are words; but what influence has it on the application of language?

573. Is it through the impossibility of anything’s convincing me of the contrary?

574. The question is, what kind of proposition is: “I know I can’t be mistaken about that”, or again “I can’t be mistaken about that”? This “I know” seems to prescind from all grounds: I simply know it. But if there can be any question at all of being mistaken here, then it must be possible to test whether I know it.

575. Thus the purpose of the phrase “I know” might be to indicate where I can be relied on; but where that’s what it’s doing, the usefulness of this sign must emerge from experience.

576. One might say “How do I know that I’m not mistaken about my name?” – and if the reply was “Because I have used it so often”, one might go on to ask “How do I know that I am not mistaken about that?” And here the “How do I know” cannot any longer have any significance.

577. “My knowledge of my name is absolutely definite.”
I would refuse to entertain any argument that tried to show the opposite!
And what does “I would refuse” mean? Is it the expression of an intention?

578. But mightn’t a higher authority assure me that I don’t know the truth? So that I had to say “Teach me!” ? But then my eyes would have to be opened.

579. It is part of the language-game with people’s names that everyone knows his name with the greatest certainty.

580. It might surely happen that whenever I said “I know” it turned out to be wrong. (Showing up.)

581. But perhaps I might nevertheless be unable to help myself, so that I kept on declaring “I know…”. But ask yourself: how did the child learn the expression?

582. “I know that” may mean; I am quite familiar with it – or again: it is certainly so.

583. “I know that the name of this in…is…” – How do you know? – “I have learnt…”. Could I substitute “In…the name of this is…” for “I know etc” in this example?

584. Would it be possible to make use of the verb “know” only in the question “How do you know?” following a simple assertion? – Instead of “I already know that” one says “I am familiar with that”; and this follows only upon being told the fact. But what does one say instead of “I know what that is”?

585. But doesn’t “I know that that’s a tree” say something different from “that is a tree”?

586. Instead of “I know what that is” one might say “I can say what that is”. And if one adopted this form of expression what would then become of “I know that that is a…”?

587. Back to the question whether “I know that that’s a…” says anything different from “that is a…”. In the first sentence a person is mentioned, in the second, not. But that does not show that they have different meanings. At all events one often replaces the first form by the second, and then often gives the latter a special intonation. For one speaks differently when one makes an uncontradicted assertion from when one maintains an assertion in face of contradiction.

588. But don’t I use the words “I know that…” to say that I am in a certain state, whereas the mere assertion “that is a…” does not say this? And yet one often does reply to such an assertion by asking “how do you know?” – “But surely, only because the fact that I assert this gives to understand that I think I know it.” – This point could be made in the following way: in a zoo there might be a notice “this is a zebra”; but never “I know that this is a zebra”. “I know” has meaning only when it is uttered by a person. But, given that, it is a matter of indifference whether what is uttered is “I know…” or “That is…”.

589. For how does a man learn to recognize his own state of knowing something?

590. At most one might speak of recognizing a state, where what is said is “I know what that is”. Here one can satisfy oneself that one really is in possession of this knowledge.

591. “I know what kind of tree that is. – It is a chestnut.”
“I know what kind of tree that is. – I know it’s a chestnut.”

The first statement sounds more natural than the second. One will only say “I know” a second time if one wants especially to emphasize certainty; perhaps to anticipate being contradicted. The first “I know” means roughly: I can say.
But in another case one might begin with the observation “that’s a…”, and then, when this is contradicted, counter by saying: “I know what sort of tree it is”, and by this means lay emphasis on being sure.

592. “I can tell you what kind of a… that is, and no doubt about it.”

593. Even when one can replace “I know” by “It is…” still one cannot replace the negation of the one by the negation of the other.
With “I don’t know…” a new element enters our language-games.

594. My name is “L.W.” And if someone were to dispute it, I should straightaway make connexions with innumerable things which make it certain.

595. “But I can still imagine someone making all these connexions, and none of them corresponding with reality. Why shouldn’t I be in a similar case?”
If I imagine such a person I also imagine a reality, a world that surrounds him; and I imagine him as thinking (and speaking) in contradiction to this world.

596. If someone tells me his name is N.N., it is meaningful for me to ask him “Can you be mistaken?” That is an allowable question in the language-game. And the answer to it, yes or no, makes sense. – Now of course this answer is not infallible either, i.e., there might be a time when it proved to be wrong, but that does not deprive the question “Can you be…” and the answer “No” of their meaning.

597. The reply to the question “Can you be mistaken?” gives the statement a definite weight. The answer may also be: “I don’t think so.”

598. But couldn’t one reply to the question “Can you…” by saying: “I will describe the case to you and then you can judge for yourself whether I can be mistaken”?

For example, if it were a question of someone’s own name, the fact might be that he had never used this name, but remembered he had read it on some document, – but on the other hand the answer might be: “I’ve had this name my whole life long, I’ve been called it by everybody.” If that is not equivalent to the answer “I can’t be mistaken”, then the latter has no meaning whatever. And yet quite obviously it points to a very important distinction.

599. For example one could describe the certainty of the proposition that water boils at circa 100C. That isn’t e.g. a proposition I have once heard (like this or that, which I could mention). I made the experiment myself at school. The proposition is a very elementary one in our text-books, which are to be trusted in matters like this because… – Now one can offer counter-examples to all this, which show that human beings have held this and that to be certain which later, according to our opinion, proved false. But the argument is worthless. [May it not also happen that we believe we recognize a mistake of earlier times and later come to the conclusion that the first opinion was the right one? etc.] To say: in the end we can only adduce such grounds as we hold to be grounds, is to say nothing at all.

I believe that at the bottom of this is a misunderstanding of the nature of our language-games.

600. What kind of grounds have I for trusting text-books of experimental physics?

I have no grounds for not trusting them. And I trust them. I know how such books are produced – or rather, I believe I know. I have some evidence, but it does not go very far and is of a very scattered nature. I have heard, seen and read various things.

601. There is always the danger of wanting to find an expression’s meaning by contemplating the expression itself, and the frame of mind in which one uses it, instead of always thinking of the practice. That is why one repeats the expression to oneself so often, because it is as if one must see what one is looking for in the expression and in the feeling it gives one.

602. Should I say “I believe in physics”, or “I know that physics is true”?

603. I am taught that under such circumstances this happens. It has been discovered by making the experiment a few times. Not that that would prove anything to us, if it weren’t that this experience was surrounded by others which combine with it to form a system. Thus, people did not make experiments just about falling bodies but also about air resistence and all sorts of other things.

But in the end I rely on these experiences, or on the reports of them, I feel no scruples about ordering my own activities in accordance with them. – But hasn’t this trust also proved itself? So far as I can judge – yes.

604. In a court of law the statement of a physicist that water boils at about 100C would be accepted unconditionally as truth.

If I mistrusted this statement what could I do to undermine it? Set up experiments myself? What would they prove?

605. But what if the physicist’s statement were superstition and it were just as absurd to go by it in reaching a verdict as to rely on ordeal by fire?

606. That to my mind someone else has been wrong is no ground for assuming that I am wrong now. – But isn’t it a ground for assuming that I might be wrong? It is no ground for any unsureness in my judgement, or my actions.

607. A judge might even say “That is the truth – so far as a human being can know it.” But what would this rider [Zusatz] achieve? (“beyond all reasonable doubt”).

608. Is it wrong for me to be guided in my actions by the propositions of physics? Am I to say I have no good ground for doing so? Isn’t precisely this what we call a ‘good ground’?

609. Supposing we met people who did not regard that as a telling reason. Now, how do we imagine this? Instead of the physicist, they consult an oracle. (And for that we consider them primitive.) Is it wrong for them to consult an oracle and be guided by it? – If we call this “wrong” aren’t we using our language-game as a base from which to combat theirs?

610. And are we right or wrong to combat it? Of course there are all sorts of slogans which will be used to support our proceedings.

611. Where two principles really do meet which cannot be reconciled with one another, then each man declares the other a fool and heretic.

612. I said I would ‘combat’ the other man, – but wouldn’t I give him reasons? Certainly; but how far do they go? At the end of reasons comes persuasion. (Think what happens when missionaries convert natives.)

613. If I now say “I know that the water in the kettle in the gas-flame will not freeze but boil”, I seem to be as justified in this “I know” as I am in any. ‘If I know anything I know this‘. – Or do I know with still greater certainty that the person opposite me is my old friend so-and-so? And how does that compare with the proposition that I am seeing with two eyes and shall see them if I look in the glass? – I don’t know confidently what I am to answer here. – But still there is a difference between cases. If the water over the gas freezes, of course I shall be as astonished as can be, but I shall assume some factor I don’t know of, and perhaps leave the matter to physicists to judge. But what could make me doubt whether this person here is N.N., whom I have known for years? Here a doubt would seem to drag everything with it and plunge it into chaos.

614. That is to say: If I were contradicted on all sides and told that this person’s name was not what I had always known it was (and I use “know” here intentionally), then in that case the foundation of all judging would be taken away from me.

615. Now does that mean: “I can only make judgements at all because things behave thus and thus (as it were, behave kindly)”?

616. Why, would it be unthinkable that I should stay in the saddle however much the facts bucked?

617. Certain events would me into a position in which I could not go on with the old language-game any further. In which I was torn away from the sureness of the game.

Indeed, doesn’t it seem obvious that the possibility of a language-game is conditioned by certain facts?

618. In that case it would seem as if the language-game must ‘show‘ the facts that make it possible. (But that’s not how it is.)

Then can one say that only a certain regularity in occurrences makes induction possible? The ‘possible’ would of course have to be ‘logically possible‘.

619. Am I to say: even if an irregularity in natural events did suddenly occur, that wouldn’t have to throw me out of the saddle, I might make inferences then just as before, but whether one would call that “induction” is another question.

620. In particular circumstances one says “you can rely on this”; and this assurance may be justified or unjustified in everyday language, and it may also count as justified even when what was foretold does not occur. A language-game exists in which this assurance is employed.

621. If anatomy were under discussion I should say: “I know that twelve pairs of nerves lead from the brain.” I have never seen these nerves, and even a specialist will only have observed them in a few specimens. – This just is how the word “know” is correctly used here.

622. But now it is also correct to use “I know” in the contexts which Moore mentioned, at least in particular circumstances. (Indeed, I do not know what “I know that I am a human being” means. But even that might be given a sense.)
For each one of these sentences I can imagine circumstances that turn it into a move in one of our language-games, and by that it loses everything that is philosophically astonishing.

623. What is odd is that in such a case I always feel like saying (although it is wrong): “I know that – so far as one can know such a thing.” That is incorrect, but something right is hidden behind it.

624. “Can you be mistaken about this colour’s being called ‘green’ in English?” My answer to this can only be “No”. If I were to say “Yes, for there is always the possibility of delusion”, that would mean nothing at all.
For is that rider [Nachsatz] something unknown to the other? And how is it known to me?

625. But does that mean that it is unthinkable that the word “green” should have been produced here by a slip of the tongue or a momentary confusion? Don’t we know of such cases? – One can also say to someone “Mightn’t you perhaps have made a slip?” That amounts to: “Think about it again.” –

But these rules of caution only make sense if they come to an end somewhere.
A doubt without an end is not even a doubt.

626. Nor does it mean anything to say: “The English name of this colour is certainly ‘green’, – unless, of course, I am making a slip of the tongue or am confused in some way.”

627. Wouldn’t one have to insert this clause into all language-games? (Which shows its senselessness.)

628. When we say “Certain propositions must be excluded from doubt”, it sounds as if I ought to put these propositions – for example, that I am called L.W. – into a logic-book. For if it belongs to the description of a language-game, it belongs to logic. But that I am called L.W. does not belong to any such description. The language-game that operates with people’s names can certainly exist even if I am mistaken about my name, – but it does presuppose that it is nonsensical to say that the majority of people are mistaken about their names.

629. On the other hand, however, it is right to say of myself “I cannot be mistaken about my name”, and wrong if I say “perhaps I am mistaken”. But that doesn’t mean that it is meaningless for others to doubt what I declare to be certain.

630. It is simply the normal case, to be incapable of mistake about the designation of certain things in one’s mother tongue.

631. “I can’t be making a mistake about it” simply characterizes one kind of assertion.

632. Certain and uncertain memory. If certain memory were not in general more reliable than uncertain memory, i.e., if it were not confirmed by further verification more often than uncertain memory was, then the expression of certainty and uncertainty would not have its present function in language.

633. “I can’t be making a mistake” – but what if I did make a mistake then, after all? For isn’t that possible? But does that make the expression “I can’t be etc.” nonsense? Or would it be better to say instead “I can hardly be mistaken”? No; for that means something else.

634. “I can’t be making a mistake; and if the worst comes to the worst I shall make my proposition into a norm.”

635. “I can’t be making a mistake; I was with him today.”

636. “I can’t be making a mistake; but if after all something should appear to speak against my proposition I shall stick to it, despite this appearance.”

637. “I can’t etc.” shows my assertion its place in the game. But it relates essentially to me, not to the game in general.
If I am wrong in my assertion that doesn’t detract from the usefulness of the language-game.

638. “I can’t be making a mistake” is an ordinary sentence, which serves to give the certainty-value of a statement. And only in its everyday use it is justified.

639. But what the devil use is it if – as everyone admits – I may be wrong about it, and therefore about the proposition it was supposed to support too?

640. Or shall I say: the sentence excludes a certain kind of failure?

641. “He told me about it today – I can’t be making a mistake about that.” – But what if it does turn out to be wrong?! – Mustn’t one make a distinction between the ways in which something ‘turns out wrong’? – How can it be shown that my statement was wrong? Here evidence is facing evidence, and it must be decided which is to give way.

642. But suppose someone produced the scruple: what if I suddenly as it were woke up and said “Just think, I’ve been imagining I was called L.W.!” —- well, who says that I don’t wake up once again and call this an extraordinary fancy, and so on?

643. Admittedly one can imagine a case – and cases do exist – where after the ‘awakening’ one never has any more doubt which was imagination and which was reality. But such a case, or its possibility, doesn’t discredit the proposition “I can’t be wrong”.

644. For otherwise, wouldn’t all assertion be discredited in this way?

645. I can’t be making a mistake, – but some day, rightly or wrongly, I may think I realize that I was not competent to judge.

646. Admittedly, if that always or often happened it would completely alter the character of the language-game.

647. There is a difference between a mistake for which, as it were, a place is prepared in the game, and a complete irregularity that happens as an exception.

648. I may also convince someone else that I ‘can’t be making a mistake’.
I say to someone “So-and-so was with me this morning and told me such-and-such”. If this is astonishing he may ask me: “You can’t be mistaken about it?” That may mean: “Did that really happen this morning?” or on the other hand: “Are you sure you understood him properly?” It is easy to see what details I should add to show that I was not wrong about the time, and similarly to show that I hadn’t misunderstood the story. But all that can not show that I haven’t dreamed the whole thing, or imagined it to myself in a dreamy way. Nor can it show that I haven’t perhaps made some slip of the tongue throughout. (That sort of thing does happen.)

649. (I once said to someone – in English – that the shape of a certain branch was typical of the branch of an elm, which my companion denied. Then we came past some ashes, and I said “There, you see, here are the branches I was speaking about.” To which he replied “But that’s an ash” – and I said “I always meant ash when I said elm”.)

650. This surely means: the possibility of a mistake can be eliminated in certain (numerous) cases. – And one does eliminate mistakes in calculation in this way. For when a calculation has been checked over and over again one cannot then say “Its rightness is still only very probable – for an error may always still have slipped in”. For suppose it did seem for once as if an error had been discovered – why shouldn’t we suspect an error here?

651. I cannot be making a mistake about 12×12 being 144. And now one cannot contrast mathematical certainty with the relative uncertainty of empirical propositions. For the mathematical proposition has been obtained by a series of actions that are in no way different from the actions of the rest of our lives, and are in the same degree liable to forgetfulness, oversight and illusion.

652. Now can I prophesy that men will never throw over the present arithmetical propositions, never say that now at last they know how the matter stands? Yet would that justify a doubt on our part?

653. If the proposition 12×12=144 is exempt from doubt, then so too must non-mathematical propositions be.

654. But against this there are plenty of objections. – In the first place there is the fact that “12×12 etc.” is a mathematical proposition, and from this one may infer that only mathematical propositions are in this situation. And if this inference is not justified, then there ought to be a proposition that is just as certain, and deals with the process of this calculation, but isn’t itself mathematical. I am thinking of such a proposition as: “The multiplication ’12×12′, when carried out by people who know how to calculate, will in the great majority of cases give the result ‘144’.” Nobody will contest this proposition, and naturally it is not a mathematical one. But has it got the certainty of the mathematical proposition?

655. The mathematical proposition has, as it were officially, been given the stamp of incontestability. I.e.: “Dispute about other things; this is immovable – it is a hinge on which your dispute can turn.”

656. And one can not say that of the propositions that I am called L.W. Nor of the proposition that such-and-such people have calculated such-and-such a problem correctly.

657. The propositions of mathematics might be said to be fossilized. – The proposition “I am called….” is not. But it too is regarded as incontrovertible by those who, like myself, have overwhelming evidence for it. And this not out of thoughtlessness. For, the evidence’s being overwhelming consists precisely in the fact that we do not need to give way before any contrary evidence. And so we have here a buttress similar to the one that makes the propositions of mathematics incontrovertible.

658. The question “But mightn’t you be in the grip of a delusion now and perhaps later find this out?” – might also be raised as an objection to any proposition of the multiplication tables.

659. “I cannot be making a mistake about the fact that I have just had lunch.”
For if I say to someone “I have just eaten” he may believe that I am lying or have momentarily lost my wits but he won’t believe that I am making a mistake. Indeed, the assumption that I might be making a mistake has no meaning here.
But that isn’t true. I might, for example, have dropped off immediately after the meal without knowing it and have slept for an hour, and now believe I have just eaten.
But still, I distinguish here between different kinds of mistake.

660. I might ask: “How could I be making a mistake about my name being L.W.?” And I can say: I can’t see how it would be possible.

661. How might I be mistaken in my assumption that I was never on the moon?

662. If I were to say “I have never been on the moon – but I may be mistaken”, that would be idiotic.

For even the thought that I might have transported there, by unknown means, in my sleep, would not give me any right to speak of a possible mistake here. I play the game wrong if I do.

663. I have a right to say “I can’t be making a mistake about this” even if I am in error.

664. It makes a difference: whether one is learning in school what is right and wrong in mathematics, or whether I myself say that I cannot be making a mistake in a proposition.

665. In the latter case I am adding something special to what is generally laid down.

666. But how is it for example with anatomy (or a large part of it)? Isn’t what it describes, too, exempt from all doubt?

667. Even if I came to a country where they believed that people were taken to the moon in dreams, I couldn’t say to them: “I have never been to the moon. – Of course I may be mistaken”. And to their question “Mayn’t you be mistaken?” I should have to answer: No.

668. What practical consequences has it if I give a piece of information and add that I can’t be making a mistake about it?
(I might also add instead: “I can no more be wrong about this than about my name’s being L.W.”)

The other person might doubt my statement nonetheless. But if he trusts me he will not only accept my information, he will also draw definite conclusions from my conviction, as to how I shall behave.

669. The sentence “I can’t be making a mistake” is certainly used in practice. But we may question whether it is then to be taken in a perfectly rigorous sense, or is rather a kind of exaggeration which perhaps is used only with a view to persuasion.

670. We might speak of fundamental principles of human enquiry.

671. I fly from here to a part of the world where the people have only indefinite information, or none at all, about the possibility of flying. I tell them I have just flown there from… They ask me if I might be mistaken. – They have obviously a false impression of how the thing happens. (If I were packed up in a box it would be possible for me to be mistaken about the way I had travelled.) If I simply tell them that I can’t be mistaken, that won’t perhaps convince them; but it will if I describe the actual procedure to them. Then they will certainly not bring the possibility of a mistake into the question. But for all that – even if they trust me – they might believe I had been dreaming or that magic had made me imagine it.

672. “If I don’t trust this evidence why should I trust any evidence?”

673. Is it not difficult to distinguish between the cases in which I cannot and those in which I can hardly be mistaken? Is it always clear to which kind a case belongs? I believe not.

674. There are, however, certain types of case in which I rightly say I cannot be making a mistake, and Moore has given a few examples of such cases.
I can enumerate various typical cases, but not give any common characteristic. (N.N. cannot be mistaken about his flown from America to England a few days ago. Only if he is mad can he take anything else to be possible.)

675. If someone believes that he has flown from America to England in the last few days, then, I believe, he cannot be making a mistake.
And just the same if someone says that he is at this moment sitting at a table and writing.

676. “But even if in such cases I can’t be mistaken, isn’t it possible that I am drugged?” If I am and if the drug has taken away my consciousness, then I am not now really talking and thinking. I cannot seriously suppose that I am at this moment dreaming. Someone who, dreaming, says “I am dreaming”, even if he speaks audibly in doing so, is no more right than if he said in his dream “it is raining”, while it was in fact raining. Even if his dream were actually connected with the noise of the rain.